Boyden's triad: the past, present and future

The B3 downwards-shifting malformation was first proposed by Boyden in 1950. Here, we report 14 cases of this malformation in the right lung and the first case of segmentectomy for this malformation.

All patients with pulmonary lesions underwent three-dimensional computed tomography bronchography and angiography (3D-CTBA) between January 2019 and January 2020, prior to surgery. A consecutive 2356 patients were included, and 14 cases of this malformation were identified; bronchovascular patterns were analysed in each patient.

The incidence of this malformation was 0.6%. It was further divided into 3 types: over downwards-shift, partial downwards-shift and normal downwards-shift. The normal downwards-shift type was the most common (8/14), where B3 shifted downwards completely to merge with B4 + 5. In the partial downwards-shift (5/14), only part of the B3 shifted. In the over downwards-shift type (1/14), both B3 and B1b shifted downwards. A bifurcated right upper lobe （RUL) bronchus (B1 defective) was observed in 3 cases. The incidence of V1a, V1b, V2a, V2b, V2c, V3a, V3b and V3c was 100% (14/14). The incidence rates of A1, A3a and A3b were 100% (14/14). The incidence of A2 rec and A2 asc was 92.9% (13/14) and 71.4% (10/14), respectively.

The B3 downwards-shifting malformation or 'Boyden's triad' is a rare anomaly. Anatomical exploration of this malformation is important for surgery.